There was no plan. All we have is some random comments from Satoshi suggesting a possibility.
I don't know how you're defining "random" here. Satoshi wrote that he expected blocks
with 3,000 transactions/second in them if Bitcoin became successful, even before he released the first client.
When he instated the 1 MB limit, it was unambiguously created as a
temporary measure. When Satoshi was active on the forum, there was discussion on options for replacing it, with a clear implication in all of the participants' comments, including Satoshi's, that the 1 MB cap would eventually be removed if the volume of transaction data approached 1 MB:
https://bitcointalksearch.org/topic/patch-increase-block-size-limit-1347 Note how the proposal is careful to note that not voting is not a vote for a 1MB limit, but a vote for the status quo.
That's somewhat better, given the status quo will be described as 'the 1MB limit will be lifted eventually when there is consensus around a viable replacement'.
Unfortunately that just isn't possible because miners fundamentally control what votes get into the blockchain at all.
That's true. The flip side is that this voting method requires support in all major clients to be useful.
Also with regard to this voting concept in general, whether it treats normal transactions as votes or not, it gives e-wallet operators more power over the votes of those who entrust their bitcoins with them than mining pools have now over the votes of those who point their hashes to them.
"Very few"?
My off-the-cuff guess (may be wrong) for a solution was: if (todays_date > SOME_FUTURE_DATE) { MAX_BLOCK_SIZE *= 2, every 1 years } [Other devs comment: too fast!] That might be too fast, but the point is, not feedback based nor directly miner controlled.
-http://garzikrants.blogspot.de/2013_02_01_archive.html (emphasis his, not mine)
That's Jeff Garzik, a highly respected core developer. Gregory Maxwell and IIRC Pieter Wuille shared those same concerns on IRC. Gavin is the odd man out in the core-dev team to think that leaving the decision up to miners is OK.
That's not referring to voting on a protocol change. That's in reference to a protocol change that allows miners to continuously vote on a dynamic block size limit. There's a big difference between miners voting once to change the protocol, and a protocol change that allows miners to actively control the block size limit through regular voting.
All of the protocol changes so far have been voted on through the mining method, so there doesn't appear to be much opposition to this method.